1. To cause two or more things to change places or locations with each other: When Trudy's father dialed her phone number, he got the wrong person; so, he assumed that he had accidentally transposed a couple of the numbers.

When Jack L., the author, wrote about two of the characters in his novel, the Susan, the editor, noticed that every once in awhile, the writer was mistakenly transposing their names.

2. To move to a different place or context: The teacher pointed out that James had misspelled the word "strength" as "strenght" on his paper; so, she suggested that he correct it by transposing the last two letters to make the spelling correct.
3. To write or to perform a musical composition in a key other than the original or given key: Since Janet was a soprano, the piece she was supposed to sing had to be transposed higher from C major to E major.